The present invention relates to the field of well completions for producing fluids, such as petroleum and gas, from wells. More particularly, the invention relates to a technique for transporting fluids through the interior of a tubing housing a power cable for a submersible pumping system.
A variety of pumping systems have been devised and are currently in use for raising fluids from wells, such as petroleum production wells. In general, where a subterranean formation provides sufficient pressure to raise wellbore fluids to the earth""s surface, the well may be exploited directly by properly channeling the fluids through conduits and above-ground valving. However, when the subterranean formations do not provide sufficient pressure, submersible pumping systems are commonly employed force wellbore fluids to the earth""s surface for subsequent collection and processing. A packer or other fluid barrier may be placed above the pumping system to fluidicly isolate the portion of the wellbore to be pumped.
In general, one class of submersible pumping systems includes a prime mover, typically an electric motor, coupled to a pump. The electric motor and pump are positioned within wellbore fluids and the pump is driven by the electric motor to draw the fluids into the pump and to force them, under pressure, to the earth""s surface. A power cable is routed from the surface through the packer to the electric motor.
The fluids produced by the pump may be forced upwardly through the packer and various types of conduit, such as the well casing, or production tubing, to a collection point at the earth""s surface. The pumping systems may also include ancillary components, depending upon the configurations of the subterranean formations. Such components often include separators for removing oil from water or gas, and injection pumps or compressors for re-injecting water or other non-production fluids into designated subterranean formations above or below the producing horizons.
Gas from the formation or from the gas separator can collect, or be collected, under the packer. The gas may cause the submersible pumping system to fail if the volume of the gas is allowed to grow until it encompasses the fluid intake of the submersible pumping system. Therefore, a technique for venting gas through the packer to prevent the volume of gas from reaching the submersible pumping system fluid intake is desirable.
Also, it is sometimes desirable to inject chemicals or fluids into the vicinity of a subterranean formation. Such fluids may include anticorrosive agents, viscosity reducing agents, scale inhibitors, and so forth. However, unless dedicated chemical injection lines are provided in the pumping system during its deployment, such injection is often difficult or impossible to accommodate without removal of the pumping system from the well. Therefore, a technique for injecting chemicals through the packer also is desirable.
However, space constraints can limit the number of passageways that can be placed through the packer. Also, a greater number of passageways through the packer increases the difficulty of maintaining a fluid seal with the packer.
The present invention features a system for producing fluid from a wellbore. The system comprises a packer disposed within a wellbore casing. The packer defines a first and a second zone of the wellbore. The system also comprises a submersible pumping system to displace liquid from the first zone of the wellbore to a desired location via a first fluid flow path. The system also comprises tubing and a power cable disposed within the tubing to supply power to the submersible pumping system. A second fluid flow path also extends from the first zone of the wellbore. At least a portion of the second fluid flow path is disposed within the tubing.
According to another aspect of the invention, a well completion system for raising fluids from a well is featured. The well completion system comprises a packer for dividing the well into an upper zone and a lower zone. The packer has first and second passageways that extend through the packer between the upper zone and the lower zone. A pumping system is disposed in the lower zone and is operable to displace fluids from the lower zone through the first passageway via a first fluid path. A power cable for supplying power to the pumping system extends through a fluid conduit. The fluid conduit also serves as part of a second fluid path extending through the second passageway in the packer.
According to another aspect of the invention, a method for producing fluid from a wellbore is featured. The method comprises the act of deploying a completion system in the wellbore. The completion system comprises a packer, having first and second passageways therethrough and a pumping system disposed in a lower zone below the packer. The pumping system discharges fluid into the first passageway. Furthermore, the well completion system comprises a conduit having a power cable disposed therein. Fluid is directed through the conduit which is in fluid communication with the lower zone via the second passageway.
The above description of various aspects of the present invention is merely exemplary and is not intended to limit the scope of the invention.